Is there a way to put multiple links in a single bookmark in Firefox?

I’m using the bookmarks toolbar in Firefox and since so many websites now have little icons to tell me what they are, I just have a bunch of those.

Is there a way to put multiple links in one icon, so when I click it, it just opens up multiple tabs?

I tried doing it before by putting a link, then a comma, space and another link. It didn’t work.

So instead I put a folder in the toolbar, but there is no distinct icon for the folder and you can’t change it. I had to put a word there.

Are there other ways of doing this? It’s not really important, but I just like the aesthetics since I have to use the computer so much.